It seems amateur viewing angle starts to be the norm nowadays for horror films -- effective ones.
Paranormal Activity series is great, particularly the first one, which caused me to Google whether it was real. However, its sequels are not as scary, including the one in Japan, probably due to similarity of tricks.
Yes, it's all about the tricks. Haunted Changi is a Singaporean production, meaning it emphasizes on different aspect of supernatural phenomenons for viewers believing in different paranormal activities. For me, as an example, horror films lose credible feel greatly if Satan or Lucifer appears. Thus, Haunted Changi might not satisfy the taste of some Western audience.
Not all tricks Haunted Changi uses is convincing to me, but some of them are greatly effective to scare, especially one that towards the end of the film. Overall, it is a great horror film and definitely could scare the hell out of a timid mind.